San Clemente, CA and Toledo, OH -- Southern California Edison announced Friday it would permanently shutdown the troubled San Onofre nuclear power plant.

The move comes 17 months after the San Onofre plant was idled because of problems in steam generator systems.

Until now, Edison had vowed to restart the plant. But the company released a statement Friday saying it would stop the process to fire up the plant. (Los Angeles Times reports)

"This is the fourth nuclear plant to shutdown permanently in the last three months. Aging nuclear plants are proving to be unreliable and unaffordable to operate," said Arnie Gundersen, Chief Engineer at Fairewinds Associates, Inc. The four reactors’ permanent shutdown in 2013 is the most ever in a single year, according to U.S. Nuclear Regulatory Commission (NRC) data.

Gundersen serves as expert witness for Friends of the Earth (FOE), which has intervened at San Onofre calling for long overdue, full public hearings on the license amendment involved with the replacement steam generators. Gundersen, alongside other FOE spokespersons, held a press conference on a public beach immediately adjacent to San Onofre today.

Similar to the San Onofre intervention, on May 20th, an environmental coalition petitioned the NRC Atomic Safety and Licensing Board (ASLB) for license amendment hearings to intervene against the planned steam generator replacements at FirstEnergy Nuclear Operating Company's (FENOC) Davis-Besse atomic reactor. Gundersen also serves as this coalition’s expert witness, on behalf of Beyond Nuclear, Citizen Environment Alliance of Southwestern Ontario, Don’t Waste Michigan, and Sierra Club.

Davis-Besse is located in Oak Harbor, on the Lake Erie shore, just east of Toledo.

On May 29, the environmental interveners were informed by the Chief Administrative Judge of the ASLB that a panel of ASLB judges has been seated to review the intervention.

The environmental coalition’s intervention now looms large with the Friday announcement of the permanent shutdown of the San Onofre Unit 2 and 3 reactors.

Terry Lodge, attorney for the interveners, said: "The steam generator disaster at San Onofre, and the public attempt to avoid similar bungling at Davis-Besse, stem directly from the NRC's 24-year campaign to deregulate the industry. At San Onofre and Davis-Besse, the NRC relied on the utility's self-report as to whether there is anything significant about this very major feat of building and installing technologically different pieces of equipment. There has been a fiasco in three out of the last three steam generator replacements. 'Cross-my-heart-and-hope-to-die' regulation is totally unacceptable."

The coalition’s intervention petition is posted at Beyond Nuclear’s website, www.beyondnuclear.org. So too is Gundersen’s expert witness testimony. At Davis-Besse, Gundersen has declared that the “data reviewed shows that FENOC should have applied for a license amendment with the requisite public review six years ago when Replacement Steam Generators were originally designed, ordered, and purchased.”

In filings at the NRC, Gundersen has warned that there are "experimental" differences between the replacement and original steam generators at Davis-Besse. These include different metal alloys being used in the new equipment, with different supports; different accesses for inspection of internal parts; major support structure changes; thinner pressure retaining walls; and different designs of steam tube elbows. Gundersen also considers the requirement of an unprecedented fourth penetration of the reactor shield building to install the generators as an additional "experimental parameter" of the scheme.

The coalition contends that FENOC's shortcut on safety, its circumvention of an NRC license amendment proceeding, risks repeating the same sort of dangerous mistakes made at the San Onofre nuclear power plant in southern California. In January, 2012 a steam generator tube rupture at San Onofre released radioactivity to the environment, and led to the discovery of widespread, unexpected tube degradation in replacement steam generators just a year or two old.